This invention relates to improvements in detection means for detecting the non-operability of a lamp and preventing full illumination of a non-operative lamp.
When considering amusement machines such as, for example, card playing machines, one of the greatest problems is the reliability of the lamps used in the machine display. As such machines normally have inbuilt time limits and a large number of lamps, the problem of the non-operability of any one or a number of the lamps is a serious one, mainly due to the fact that a user does not know the lamp has failed.
To consider a specific example, in the U.S. Pat. No. 3,889,956 of Castle there is shown a card playing machine where, upon a particular card being illuminated the player must specifically reject the card within a certain prescribed time limit or the card is taken as having been accepted. Thus, if a particular card were selected by the machine and if the lamp for that card was non-operative, then a user would be in the position of not knowing that the particular card had been accepted and would thus not have the opportunity of rejecting the card. The card would thus be automatically accepted.
Such a situation naturally devalues the reliability and, more particularly, the integrity of such a machine as the reliability and game integrity of such a machine are dependent upon the probabilistic failure of a single display device - which may represent less than 1% of the total display complement. The ability to overcome this problem of detecting non-operative output displays has, in the past, precluded the development of a machine which was reliable and had market acceptance.
Devices for the indication of a lamp which ceases to operate are known. For example, U.S. Pat. No. 3,523,238 of Jones is directed to a device for sensing the current in a load circuit, such as runway lamps, and is directed primarily to regulating the current in such a load circuit. Referring to the Jones specification, the sensing is done by providing a constant current source for a load 1, and a current transformer 5--5 connected in series between the constant current source and the load. The secondary winding 5b of the current transformer is connected in a load monitoring circuit 3 including an inductance 6 and a capacitor 7. Upon any variation of the constant current supplied to the load 1, the potential drop across the capacitor 7 is proportional to the load current and this potential drop is supplied to a high impedance, voltage-sensitive detector 4 which, in turn, is connected to a signal device or to control means for restoring the constant current to a preset value. This restoration may be effected manually by adjustment of the constant current source 2.
Another example is U.S. Pat. No. 3,421,157 of Atkins which shows a device for indicating that a lamp has failed. In Atkins, there must be a full potential applied to the lamp to ascertain if it works. In contrast, the present invention is directed to a device which determines the operability of a particular lamp before full and continuous potential is applied to the lamp--that is, if the lamp is not operative it is isolated and no attempt is made to apply full and continuous potential to that lamp.
A further example is that of U.S. Pat. No. 3,987,424 of Brouwer et al, which is directed to a bulb outage warning system for informing an operator of the failure of a lamp by the detection of the steady state lamp current. This device operates by continually monitoring the lamp current but cannot detect the non-operability of a lamp before full potential is applied.
U.S. Pat. No. 3,710,157 of Wright discloses a control device for a pair of flashing airport runway lamps wherein both lamps are shut down if either fails. This is done by monitoring the surges of line current as the lamps flash and involves a comparison of signals. Upon a lamp failure being indicated, the other lamp is automatically disconnected. The same result could be achieved by placing each pair of lamps in series.
Winkler, in his U.S. Pat. No. 3,633,196 discloses a device for indicating the readiness of a lamp for operation. This particular device does this by providing continuous pulses to the lamps and then monitoring the result by a control circuit associated with each lamp and a separate monitoring circuit. With a display having a large number of lamps, the requirement for a control circuit for each lamp involves huge equipment expense and a large, complex structure.
The lamp burnout-detector described in U.S. Pat. No. 2,896,121 of Glandon is again a relatively complex structure which is designed to protect equipment in the case of arcing within a D.C. filament-type lamp. It does not relate to the detection of non-operability of the lamp and its selective isolation.
It is therefore the principal object of the present invention to provide a detection means for the detecting of the non-operability of a lamp and preventing the full illumination of such a non-operative lamp by selective isolation.
Another object of the invention is to provide such a detection means applicable to a plurality of lamps, for output indicia, connected together at one end and in series with the primary winding of a transformer having a secondary winding and associated circuitry operable to indicate the operativeness or the non-operativeness of any lamp upon attempted energization of the lamp.
The invention therefore provides a potential transformer having a primary winding connected in series between a source of electric potential and the illuminating devices, and having a secondary winding. The primary winding has a potential applied thereacross responsive to application of an electric potential to an illuminating device, resulting in a back E.M.F. being generated in the secondary winding. A transistorized amplifier circuit, a monostable multi-vibrator, and a memory element J-K are then used to control the illumination of the lamps.